Paper sheet package, and printer using the package

ABSTRACT

Print sheets  7  stacked up are inserted into a package member  8  so that the sheets  7  in this state can be set in a printer together with the package member  8 . The package member  8  is provided with an identification mark  31  while the printer is equipped with a reflective sensor so that the identification mark  31  will be placed in a reading area of the reflective sensor only when the sheet package  9  is loaded in the printer in a correct direction.

TECHNICAL FIELD

The present invention relates to a configuration of a sheet packagewhich stores a stack of sheets for a printer, and a configuration of aprinter using such a sheet package.

BACKGROUND OF THE INVENTION

Direct thermal printers equipped with a line thermal head have been wellknown. Into such a direct thermal printer, heat-sensitive sheets in theform of out sheets are stacked up and loaded. Some of such printers areconfigured to accommodate a sheet package in which numbers ofheat-sensitive sheets are stacked up and wrapped by a package member.

In the printer, the sheets are fed into the thermal head one by one andeach line orthogonal to the sheet feed direction is heated by thethermal head, by which arbitrary letters, images, etc. are printed onthe sheets. As the heat-sensitive sheets, various types of sheets suchas heat-coloring sheets and heat-perforated sheets can be used.

The heat-coloring sheet includes a base layer such as paper, aheat-sensitive record layer formed by applying a heat-coloring materialon the base layer, and an overcoat layer formed by applyingultraviolet-curing resin, etc. on the heat-sensitive record layer andirradiating the resin with ultraviolet rays. When such a heat-coloringsheet is heated by the thermal head from the side of the overcoat layer(print surface), the heat-sensitive record layer in the heated partchanges color. As a type of heat-coloring sheet, there exists amulticolor heat-sensitive sheet having a plurality of coloring layers.When the thermal head heats such a multicolor heat-sensitive sheet fromthe side of the coloring layers (print surface) while adjusting theamount of thermal energy, the heat-sensitive record layer in the heatedpart changes color accordingly.

The heat-perforated sheet includes a thermoplastic film, a porous base,and an adhesive layer for bonding them together. When such aheat-perforated sheet is heated by the thermal head of the printer fromthe side of the thermoplastic film (print surface), the thermoplasticfilm is perforated to change color of the sheet in a desired pattern(character string, etc.).

DISCLOSURE OF THE INVENTION

In either type of existing heat-sensitive sheet explained above, theprinting is impossible when the heat-sensitive sheet is heated by thethermal head from a side opposite to the print surface. However, userssometimes set sheets in a printer in a wrong direction, and erroneouslysetting the sheets upside down results in failure of printing.

As another type of sheet for printing, there exists a duplicate sheetdesigned to allow simultaneous printing on two sheets. The duplicatesheet is formed by stacking up two sheets and bonding them togetheralong one side. The duplicate sheet has to be set with the bonded partplaced at the front end in the sheet feed direction, and loading thesheet back to front causes a paper jam in the printer.

Therefore, in a possible distribution pattern, the process for makingthe sheet package by inserting the sheets into the package member may becarried out by the manufacture, and each user may purchase the sheets inthe form of the sheet package and use the sheets by setting the sheetpackage in the printer. In this case, the insertion of the sheets intothe package member is done by the manufacturer and thus setting thesheets in a wrong direction is almost impossible in this process.

However, even in this case, the process of setting the sheet package inthe printer is done by the user and there is a possibility that the usersets the sheet package in a wrong direction, resulting in printertrouble.

It is therefore the primary object of the present invention to provide asheet package and a printer using the sheet package, capable of lettingthe user set the sheet package in the printer in the correct directionand thereby preventing failure and trouble in printing.

In accordance with an aspect of the present invention, there is provideda sheet package comprising sheets as print mediums for a printer and apackage member surrounding the sheets which have been stacked up, whichis configured so that the sheets can be set in the printer together withthe package member exposing part of the sheets. In the sheet package,the package member is provided with an identification mark so that theidentification mark will be placed in a reading area of a sensorprovided in the printer only when the sheet package is set in theprinter in a correct direction.

By the above configuration of the sheet package, when the sheet packageis set in the printer in a wrong direction, the erroneous setting can bedetected by the printer. Therefore, print failure/trouble can beprevented by letting the user set the sheet package in the correctdirection.

Preferably, the sheet package is configured so that the identificationmark will be placed in the reading area of the sensor provided in theprinter only when the sheet package is set in the printer in the correctdirection and the sheets are partially exposed from the package member.

With this configuration, setting the sheet package in the printer beforeopening the package can also be detected, by which print failure/troublecan be prevented more securely.

The package member may be integrally provided with a flap part so thatthe flap part can be set in a closed state in which the sheets aretotally covered by the package member and in an opened state in whichthe sheets are partially exposed. In this case, the flap part may beprovided with the identification mark so that the identification markwill be placed in the reading area of the sensor provided in the printerwhen the flap part has been set in the opened state.

An error mark for letting the sensor detect an error may be formed at aposition on the package member that corresponds to a position where theidentification mark exists when the flap part is in the opened state.The error mark is placed in the reading area of the sensor of theprinter when the sheet package is set in the printer with the flap partclosed.

The identification mark may indicate information on the sheets. By suchconfiguration, the identification mark can also be used for automaticjudgment on the type, thickness, etc. of the sheets stored in the sheetpackage.

The identification mark may be formed by a plurality of indicator bits.By such configuration, a plurality of sheet types can be indicated byvarious combination patterns of the indicator bits, enabling automaticjudgment by the sensor of the printer. Due to the simple bit indication,the structure of the sensor for reading the information can besimplified and thereby the cost of the printer can be reduced.

An error mark for letting the sensor detect an error may be formed atevery part of the sheet package or the sheets that can be placed in thereading area of the sensor when the sheet package is set in the printerin an incorrect direction.

With this configuration, the error mark is necessarily placed at theposition of the sensor when the sheet package is set in the printer inan incorrect direction, by which the setting error can be detectedwithout fail.

The error mark may be formed by a plurality of indicator bits indicatingthe same information, by which the error mark can be configured bysimple composition.

An error mark for letting the sensor detect an error may be formed at apart of the sheet package or the sheets that can be placed in thereading area of the sensor when the sheet package is set in the printerback to front.

An error mark for letting the sensor detect an error may be formed at apart of the sheet package or the sheets that can be placed in thereading area of the sensor when the sheet package is set in the printerupside down.

In accordance with another aspect of the present invention, there isprovided a system comprising: a sheet package including sheets as printmediums and a package member surrounding the sheets stacked up; and aprinter using the sheet package. In the system, the printer includes asensor. The sheet package is configured so that the sheets can be set inthe printer together with the package member exposing part of thesheets. The package member is provided with an identification mark sothat the identification mark will be placed in a reading area of thesensor of the printer only when the sheet package is set in the printerin a correct direction. The printer operates depending on whether theidentification mark can be read by the sensor or not.

The printer may be configured to inform a user of an error when theidentification mark can not be read by the sensor.

With this configuration, the user setting the sheet package in anincorrect direction is informed of the error and can quickly cope withthe situation by resetting the sheet package in the correct direction.

The printer may also be configured to regulate its sheet feed operationwhen the identification mark can not be read by the sensor.

The identification mark may indicate information on the sheets, and theprinter may recognize the type of the sheets by letting the sensor readthe information on the sheets indicated by the identification mark.

With this configuration, the printer reading the identification mark canautomatically judge the type of the sheets stored in the sheet packagealong with detecting that the direction of the sheets is correct.Printer control (control of sheet feed speed, the printing head, etc.)becomes possible based on the information.

The identification mark may be formed by a plurality of indicator bits,and the printer may include a plurality of sensors corresponding to theindicator bits forming the identification mark.

With this configuration, the printer can recognize the direction of thesheet package and the type of the sheets stored in the sheet package byletting the sensors read the combination of corresponding indicatorbits.

An error mark for letting the sensor detect an error may be formed atevery part of the sheet package or the sheets that can be placed in thereading area of the sensor when the sheet package is set in the printerin an incorrect direction. The error mark is formed by a plurality ofindicator bits indicating the same information. The printer isconfigured to inform the user of an error and regulate its sheet feedoperation when all the sensors read the same value.

With this configuration, in the case where the same value is read by allthe sensors, the printer judges that one of the error marks has beenread by the sensors due to incorrect setting of the sheet package, bywhich sheet feed operation with the incorrect sheet setting can beavoided and thereby the print failure/trouble can be prevented fromoccurring.

The sensor may be implemented by a reflective sensor, by which therecognition and reading of the identification mark can be attained by asensor of simple composition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a sheet package before being loaded in aprinter seeing the sheet package from above.

FIG. 2 is a perspective view of the sheet package before being loaded inthe printer seeing the sheet package from below.

FIG. 3 is an enlarged view showing a part of the sheet package on whichan identification mark is formed.

FIG. 4 is a perspective view showing the sheet package with its flappart closed.

FIG. 5 is a developed view of the sheet package.

FIG. 6 is a perspective view of the printer.

FIG. 7 is a sectional side view of the printer.

FIG. 8 is a perspective view showing a sheet storage unit of theprinter.

FIG. 9 is a sectional side view showing a state in which the sheets areset in the sheet storage unit.

FIG. 10 is an enlarged sectional view showing the details of a sheetseparation unit and a print mechanism unit.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, a description will be given in detail ofpreferred embodiments in accordance with the present invention.

First, a sheet package 9 will be explained below referring to FIGS. 1through 5.

FIG. 1 is a perspective view of the sheet package before being loaded ina printer, seeing the sheet package from above. FIG. 2 is a perspectiveview of the sheet package seeing it from below. FIG. 3 is an enlargedview showing a part of the sheet package on which an identification markis formed.

As shown in FIG. 1, the sheet package 9 includes heat-sensitive paper 7in the form of small-sized cut sheets of approximately A6-A7 size forexample (print medium, hereinafter referred to as “sheets 7”) and apackage member 8 surrounding the sheets 7 which are stacked up.

The sheet package 9 is a package formed by storing a stack of the sheets7 described above in the package member 8, as shown in FIG. 4. A userpurchases the sheet package 9 in the state shown in FIG. 4, partiallyexposes the sheets 7 from the package member 8 as shown in FIG. 1 by aprescribed procedure, and sets the sheet package 9 in a printer 1.Incidentally, when a flap part 8 a is opened, a tear-off part 45 is cutoff along perforations 46.

The package member 8 is formed by folding a plane cardboard materialinto a box shape. The cardboard material before being folded is shown inFIG. 5. The cardboard material includes a first wrapping part 51, asecond wrapping part 43, a tongue part 8 b and the flap part 8 a whichare integrally formed around a base 40 which is in almost the same(rectangular) shape as the sheet 7. Incidentally, thin chain lines inFIG. 5 indicate creased parts, which facilitates the folding of thecardboard material and the assembly of the package member 8.

As shown in FIG. 1, the foldable flap part 8 a is formed integrally withthe package member 8. FIG. 1 shows a state in which the foldable flappart 8 a is folded down to the base 40 and fixed. In this state, a partof the stacked sheets 7 at an end in the lengthwise direction (sheetfeed direction) exposes its lower surface as shown in FIG. 1. The sheetpackage 9 in the state of FIG. 1 is loaded in the printer 1 which willbe explained later.

In order to fix the flap part 8 a in the state of FIG. 1, a first cut 41is made into the lower surface of the package member 8 so that the tipof the flap part 8 a can be inserted therein.

Meanwhile, a second cut 42 is made into the upper surface of the packagemember 8 (the tongue part 8 b which will be described later). The flappart 8 a (originally in the state of FIG. 1) can also be foldedoppositely toward the upper surface of the package member 8 and its tipcan be inserted into the second cut 42, by which the flap part 8 a canalso be fixed in a state covering the sheets 7.

When the sheet package 9 is set in the printer, the tongue part 8 b onthe top of the sheets 7 is situated between a pressure board 18(explained later) and the sheets 7. In the sheet feed operation of theprinter, the sheets 7 are separated one by one and conveyed smoothly bycausing proper friction between the tongue part 8 b and the sheets 7.

FIG. 2 views the sheet package 9 from below. As shown in FIG. 2, acorner of the lower surface of the package member 8 (opposite to theside exposing the sheets 7) is provided with a rectangularidentification mark 31. When the sheet package 9 is set in the printer 1in the correct direction, the identification mark 31 is placed in areading area of a reflective sensor 32 (see FIG. 8) of the printer 1 aswill be described later. The identification mark 31 has a width W and alength L in the width direction and the lengthwise direction of thesheets 7.

The identification mark 31 is composed of four rectangular indicatorbits 31 a-31 d as shown in FIG. 3. Among the four bits, 0-3 bits arecolored black and remaining one bit is not colored (remains in the color(white) of the foundation of the package member 8). In the example ofFIG. 2, the indicator bits 31 a, 31 c and 31 d are colored black, whilethe remaining bit 31 b is left white. The identification mark 31 can beformed by known methods such as printing.

The black/white pattern has been preset depending on the type of sheet(heat-sensitive paper of a normal type, heat-sensitive paper capable ofgaining two colors, label paper, duplicate paper allowing simultaneousprinting on two sheets, etc.) stored in the package member 8. Theprinter 1 recognizes the sheet type automatically by reading the patternby the reflective sensor 32 (described later).

On the lower surface of the sheet package 9 shown in FIG. 2, at theopposite corner at the end of a diagonal line drawn from theidentification mark 31, the sheets 7 are exposed from the package member8 at least by the size W (width)×L (length) of the identification mark31. The part forms an error mark E as explained below.

In this embodiment, the reflective sensor 32 regards an all-white markas an error mark (explained later in detail). Therefore, the exposedpart of the sheets (W (width)×L (length)) functions as an error mark.

It is unnecessary to form a particular error mark in cases where thepackage member 8 is white or the sheets stored in the package member 8are white, that is, no problem occurs if the part that can face thereflective sensor 32 when the sheet package 9 is set in a wrongdirection is white. In cases where the sheets 7 or the package member 8is nonwhite, a particular error mark is formed by coloring the W×L partwhite by means of printing, etc.

Such error marks E are formed also on the upper surface of the sheetpackage 9 as shown in FIG. 1. The package member 8 exposes its corners(that come to the same positions as the aforementioned identificationmark 31 and error mark E when the sheet package 9 is set upside down) atleast by the size W (width)×L (length) of the identification mark 31,which serves as the error marks E.

In the following, the overall configuration of the printer 1 will bedescribed referring to FIGS. 6 through 10.

FIG. 6 is a perspective view of the printer. FIG. 7 is a sectional sideview of the printer. FIG. 8 is a perspective view showing a sheetstorage unit of the printer. FIG. 9 is a sectional side view showing astate in which the sheets are set in the sheet storage unit. FIG. 10 isan enlarged sectional view showing the details of a sheet separationunit and a print mechanism unit.

As shown in FIG. 6, the printer 1 is formed compact in size, with arectangular shape of approximately A6 size or A7 size in a plan view anda thickness of approximately 2 cm or less.

The printer 1 has a body case 2. The body case 2 includes a frame 3, alower cover 4 covering the bottom of the frame 3, and an upper cover 5covering part of the top of the frame 3.

In a part of the upper part of the frame 3 that is not covered with theupper cover 5, a sheet storage unit (sheet supply unit) 6 is formed asshown in FIG. 3. In the sheet storage unit 6, the sheet package 9 isinserted and set.

The top of the sheet storage unit 6 is covered with a lid 10, which isrotatable with respect to the body case 2 as shown in FIG. 7. The bodycase 2 is provided with an unshown lock mechanism, by which the lid 10can be locked at a closed position as shown in FIG. 9 with the sheetpackage 9 loaded in the sheet storage unit 6 as described above.

At one end of the sheet storage unit 6, a sheet separation unit 11including a pickup roller 12, a separation block 13, etc. is placed.Beneath the upper cover 5, a print mechanism unit 14 (described indetail later) including a thermal head 15, a platen roller 16 and apaper guide 17 is placed.

At the other end of the sheet storage unit 6, the reflective sensor 32is provided to a corner on the bottom of the sheet storage unit 6 asshown in FIG. 8. The reflective sensor 32 includes four sensors 32 a-32d arranged in a line corresponding to the aforementioned indicator bits31 a-31 d. Each sensor 32 a-32 d emits light and measures reflectedlight, by which the state (black or white) of each correspondingindicator bit 31 a-31 d of the identification mark 31 is detected.

The sheet separation unit 11 will be explained below.

As shown in FIG. 10, to one end of the sheet storage unit 6 in thevicinity of the print mechanism unit 14 (right-hand side in FIG. 10),the pickup roller 12 and the separation block 13 are provided. On theinner surface of the lid 10 facing the sheet storage unit 6, a pressureplate 18 is supported rotatably. A coil spring 19 is placed between thepressure plate 18 and the lid 10 so as to constantly exert pressure onthe pressure plate 18 to rotate it downward.

The aforementioned sheet package 9 is set in the sheet storage unit 6,with the lower surface of the lowermost one of the stacked sheets 7(stacked up and stored in the package member 8 with their print surfacesfacing downward) being exposed partially from the package member 8 asshown in FIG. 9. When the lid 10 is closed and locked, the pressureplate 18 (pressed downward by the aforementioned spring 19) presses theexposed part of the sheet 7 against the pickup roller 12 via the tonguepart 8 b of the package member 8, letting the lower surface of the sheet7 contact the pickup roller 12.

The separation block 13, provided in the vicinity of the pickup roller12, has a separation guide surface 13 a being tilted with respect to thesheet feed direction of the pickup roller 12.

In this configuration, the pickup roller 12 which is driven and rotatedexerts feeding force on the lowermost sheet 7 contacting the pickuproller 12. As a principle, the lowermost sheet 7 is conveyed by thefeeding force of the pickup roller 12 (caused by the spring 19)exceeding braking force from the separation guide surface 13 a andnegative frictional force from a (second) sheet on the conveyed sheet.The second lowermost sheet on the conveyed sheet receives positivefrictional force from the lowermost sheet, negative frictional forcefrom a third lowermost sheet and braking force from the separation guidesurface 13 a and thereby stays at its position with the force balance,by which multi feeding is avoided. With the separating function of theseparation guide surface 13 a of the separation block 13, only one sheet7 at the bottom of the stacked sheets is separated and conveyed out ofthe sheet package 9.

The print mechanism unit 14 will be explained below.

The platen roller 16 is rotatably provided next to the separation block13 (on the right-hand side of the separation block 13 in FIG. 10), andthe paper guide 17 is placed close to the exterior surface of the platenroller 16. As shown in an enlarged view of FIG. 10, the paper guide 17has a sliding surface 17 a which is formed to have a concave sectionalform like a tilted letter “U” along the exterior surface of the platenroller 16. Between the paper guide 17 and the body case 2, a pressurecoil spring 20 is placed so as to press the sliding surface 17 a againstthe exterior surface of the platen roller 16.

In this configuration, the sheet 7 separated by the aforementioned sheetseparation unit 11 is conveyed by the pickup roller 12 and therebypasses through a gap between the bottom of the separation block 13 and aguide plate 21 for guiding the sheet 7 toward the platen roller 16.

The sheet 7 is guided by the guide plate 21 and fed beneath the platenroller 16 to a gap between the platen roller 16 and the paper guide 17.The sheet 7, held between the exterior surface of the platen roller 16and the sliding surface 17 a of the paper guide 17, is conveyed by therevolving platen roller 16 upward being turned over in the tilted Ushape and reaches the top of the platen roller 16 with its print surfacefacing upward.

The thermal head 15, placed nearby the top of the platen roller 16, hasa heating element unit 15 a as a printing unit. The thermal head 15 isprovided to be rotatable around a rotation axis 15 b, by which theheating element unit 15 a can contact and separate from the top of theplaten roller 16.

Incidentally, the thermal head 15 is designed to be rotatable as aboveso that the thermal head 15 will not disturb a “jammed paper clearanceoperation” when the sheet 7 has got jammed between the platen roller 16and the paper guide 17.

To the thermal head 15, an end of a spring 22 of a twisting coil springtype is attached, by which force for pressing the heating element unit15 a against the top of the platen roller 16 applied to the thermal head15 constantly.

In this configuration, the heating element unit 15 a of the thermal head15 makes contact with the upper surface of the sheet (conveyed by theplaten roller 16 with its print surface facing upward as above) and theprinting on the sheet 7 is carried out at the contacting part.

The thermal head 15, formed as a line head, is capable of printingarbitrary letters, images, etc. on the conveyed heat-sensitive sheet 7,by executing printing on each line orthogonal to the sheet feeddirection. The print width on each line is set to a width which isapproximately the same as the width of the sheet 7 as the target ofprinting.

Such a thermal head 15 is employed as the printing head for thefollowing reasons. By use of the heat-sensitive sheets as the recordmediums, consumable items like ink, ink ribbons, etc. become unnecessaryand mechanisms such as an ink supply mechanism can be left out, by whichthe printer 1 can be designed compact in size.

On the aforementioned separation block 13, a sheet ejection guidesurface 13 b, being tilted relative to the sheet feed direction of theplaten roller 16, is formed.

The sheet 7 after being printed by the heating element unit 15 a of thethermal head 15 is guided by the sheet ejection guide surface 13 b andthereby ejected to the upper side of the lid 10 through a gap betweenthe lid 10 and the upper cover 5 of the body case 2, as shown in FIG. 6.

As explained above, in the printer 1 of this embodiment, each sheet 7 isconveyed so that the lower surface of the sheet 7 set in the sheetstorage unit 6 will face the thermal head 15 for printing. Therefore,the sheets have to be set in the sheet storage unit 6 correctly (so asnot to be upside down) with their print surfaces (heat-sensitivesurfaces) facing downward.

To meet the requirement, in this embodiment, the sheets 7 are stored inthe package member 8 in the correct direction by the manufacturer. Theuser purchases the sheet package 9 and sets it in the printer 1 avoidingthe upside-down setting, by which each sheet 7 can be fed to the printmechanism unit 14 in the correct direction.

However, if the user sets the sheet package 9 upside down, a sheet feederror occurs. In this embodiment, the upside-down setting causes directcontact of the tongue part 8 b with the pickup roller 12. In this case,in addition to the sheet feed error, strong friction developing betweenthe pickup roller 12 and the tongue part 8 b might overload a motorwhich drives the pickup roller 12.

Further, since the package member 8 of the sheet package 9 is opened atone end in its lengthwise direction and closed at the other end as shownin FIG. 1, the sheet package 9 has to be set correctly (avoidingback-to-front setting) so that the opened end will face toward the printmechanism unit 14. The back-to-front setting of the sheet package 9makes the sheet feed operation totally impossible.

To eliminate such trouble, the sheet package 9 of this embodiment isprovided with the identification mark 31 on the package member 8. Theidentification mark 31 is configured to be placed in the reading area ofthe reflective sensor 32 (formed as shown in FIG. 8) only when the sheetpackage 9 is set in the printer 1 correctly avoiding the upside-down orback-to-front setting. If the sheet package 9 is loaded in the sheetstorage unit 6 in a wrong direction, one of the aforementioned threeerror marks E necessarily comes to the position of the reflective sensor32, by which the setting error of the sheet package 9 can be detectedwithout fail.

Incidentally, there is a possibility that the user erroneously sets aclosed sheet package 9 (with the flap part 8 a closed) in the printer.This also causes the sheet feed error, and thus some countermeasurebecomes necessary.

In this embodiment, the dimensions of the sheet storage unit 6 of theprinter 1 and those of the sheet package 9 are determined so that thesheet package 9 can not be set in the printer 1 (the lid 10 of theprinter 1 can not be closed) unless the sheet package 9 is opened andthe flap part 8 a is folded down to the base as shown in FIG. 1. Thus,the sensor 32 is not required to detect the unopened state of the sheetpackage 9.

It is also possible to let the sensor 32 detect the unopened state (withthe flap part 8 a closed). The detection becomes possible by thefollowing configuration, for example. First, an error mark is alsoprovided to the position of the identification mark 31 shown in FIG. 2,in place of the identification mark. Further, the size and the shape ofthe flap part 8 a is set so as to hide the error mark when the flap part8 a is folded down to the base. Further, an identification mark isformed on the part of the flap part 8 a facing the sensor 32 when theflap part 8 a is folded down to the base (i.e. the part hiding the errormark).

By such a configuration, the error mark faces the sensor 32 when thesheet package 9 is unopened. When the sheet package 9 has been openedand the flap part 8 a has been folded down to the base (when the flappart 8 a has been opened), the error mark is hidden by the flap part 8 aand the identification mark 31 on the flap part 8 a faces the sensor 32.

In this case, the error mark is also provided to proper parts of theunopened sheet package 9 so that an error mark will face the sensor 32when the unopened package is set in a wrong direction.

When a print instruction is supplied from an upper-level device (e.g., apersonal computer) connected with the printer, the sensors 32 a-32 d ofthe reflective sensor 32 read the black/white pattern which is formed bythe indicator bits 31 a-31 d of the identification mark 31. Since thepattern has been associated with a particular type of sheet as mentionedabove, the printer can automatically judge the sheet type and therebycan control driving speeds of rollers and current supply to the thermalhead automatically.

Since the identification mark 31 includes four indicator bits 31 a-31 d,the number of possible black/white combination patterns of theidentification mark 31 (i.e. the number of sheet types that can beindicated by the mark) is 2⁴=16 theoretically.

However, among the 16 patterns, the all-white pattern (with all the fourindicator bits being white) is not employed as the identification mark31.

The all-white pattern is avoided for the discrimination of theidentification mark 31 from the aforementioned error mark E. In thisembodiment, a totally white part is regarded as the error mark E, andthus all the four sensors 32 a-32 d read “white” when the error mark Eis in the reading area of the reflective sensor 32. The printer 1 ofthis embodiment judges that the direction of the sheet package isincorrect or the sheet package 9 is unopened when all the sensors 32a-32 d detect “white”. In this case, an unshown judgment unit judges theoccurrence of the error and thereby a proper notification means informsthe user of the error by alarm display (error indicator), alarm sound(buzzer), etc. to let the user cope with the situation.

In short, the all-white pattern (with four white bits) is not employedas the identification mark 31 so that such errors can securely bediscriminated from the normal state in which the sheet package 9 is setcorrectly.

Further, an all-black pattern (with all the four indicator bits beingblack) is also not employed as the identification mark 31.

The all-black pattern is avoided for letting the printer 1 recognize anempty state with no sheet package 9 loaded in the sheet storage unit 6.With no sheet in the sheet storage unit 6, there is no object forreflecting the light emitted from the sensors 32 a-32 d, by which“black” is detected by all the sensors 32 a-32 d. Based on the fact, theprinter 1 of this embodiment is configured to inform the user of theerror when the sensors 32 a-32 d detect the all-black pattern, similarlyto the above case of the error mark E.

In short, the all-black pattern (with four black bits) is not employedas the identification mark 31 so that such an error can securely bediscriminated from the normal state in which the sheet package 9 is setcorrectly.

As described above, according to the embodiment of the presentinvention, when the sheet package 9 is loaded in the printer 1 in anincorrect direction, not the identification mark 31 but an error mark Eis read by the reflective sensor 32 and thereby the user is informed ofthe error. Therefore, the user can reset the sheet package 9 in thecorrect direction avoiding the upside-down or back-to-front setting, bywhich failure and trouble in printing can be prevented.

The type of sheet can also be judged automatically by the detection ofthe information indicated by the identification mark, enabling automaticcontrol of the printer depending on the sheet type.

Further, the simple indication of the information by several indicatorbits allows simplification of the sensor for reading the information.The reflective sensor can be configured simply by arranging severalsensors in a line corresponding to the indicator bits for example, bywhich the manufacturing cost can be reduced.

While the printer in the above embodiment only informs the user of anerror when the error is detected by the reflective sensor 32, theprinter may also be configured to automatically control its operation inthis situation. In the case where the same value is read by all thesensors (all “white” or all “black”), the printer may also regulate itssheet feed operation along with informing the user of the error, bywhich the print failure/trouble can be prevented from occurring even ifthe user does not notice the error.

As set forth hereinabove, by the present invention, erroneous setting ofthe sheet package in the printer in an incorrect direction can beavoided and thereby the print failure/trouble can be prevented fromoccurring.

While the above embodiment has been presented as an illustration,various modifications can be made to the embodiment regarding the sizes,shapes, etc. of the flap part, the wrapping parts and the tongue part ofthe sheet package. The configuration of the identification mark and thesensor for reading the mark can also be modified in various ways, suchas employing bar codes as the identification mark. Thus, the presentinvention is not to be restricted by the above particular illustrativeembodiment but to be appreciated on the basis of the appended claims.

1. A sheet package, comprising: sheets as print mediums for a printer;and a package member surrounding the sheets which have been stacked up,the sheet package being configured so that the sheets can be set in theprinter together with the package member exposing part of the sheets,wherein the package member includes an identification mark so that theidentification mark will be placed in a reading area of a sensorprovided in the printer only when the sheet package is set in theprinter in a correct direction.
 2. The sheet package according to claim1, wherein the sheet package is configured so that the identificationmark will be placed in the reading area of the sensor provided in theprinter only when the sheet package is set in the printer in the correctdirection and the sheets are partially exposed from the package member.3. The sheet package according to claim 2, wherein the package member isintegrally provided with a flap part so that the flap part can be set ina closed state in which the sheets are totally covered by the packagemember and in an opened state in which the sheets are partially exposed,and wherein the flap part is provided with the identification mark sothat the identification mark will be placed in the reading area of thesensor provided in the printer when the flap part has been set in theopened state.
 4. The sheet package according to claim 3, wherein anerror mark for letting the sensor detect an error is formed at aposition on the package member that corresponds to a position where theidentification mark exists when the flap part is in the opened state,and wherein the error mark is placed in the reading area of the sensorof the printer when the sheet package is set in the printer with theflap part closed.
 5. The sheet package according to claim 1, wherein theidentification mark indicates information on the sheets.
 6. The sheetpackage according to claim 5, wherein the identification mark is formedby a plurality of indicator bits.
 7. The sheet package according toclaim 1, wherein an error mark for letting the sensor detect an error isformed at every part of the sheet package or the sheets that can beplaced in the reading area of the sensor when the sheet package is setin the printer in an incorrect direction.
 8. The sheet package accordingto claim 7, wherein the error mark is formed by a plurality of indicatorbits indicating the same information.
 9. The sheet package according toclaim 1, wherein an error mark for letting the sensor detect an error isformed at a part of the sheet package or the sheets that can be placedin the reading area of the sensor when the sheet package is set in theprinter back to front.
 10. The sheet package according to claim 1,wherein an error mark for letting the sensor detect an error is formedat a part of the sheet package or the sheets that can be placed in thereading area of the sensor when the sheet package is set in the printerupside down.
 11. A system, comprising: a sheet package including sheetsas print mediums and a package member surrounding the sheets stacked up;and a printer using the sheet package, wherein the printer includes asensor, wherein the sheet package is configured so that the sheets canbe set in the printer together with the package member exposing part ofthe sheets, the package member being provided with an identificationmark so that the identification mark will be placed in a reading area ofthe sensor of the printer only when the sheet package is set in theprinter in a correct direction, and wherein the printer operatesdepending on whether the identification mark can be read by the sensoror not.
 12. The system according to claim 11, wherein the printer isconfigured to inform a user of an error when the identification mark cannot be read by the sensor.
 13. The system according to claim 11, whereinthe printer is configured to regulate its sheet feed operation when theidentification mark can not be read by the sensor.
 14. The systemaccording to claim 12, wherein the identification mark indicatesinformation on the sheets, and wherein the printer recognizes the typeof the sheets by letting the sensor read the information on the sheetsindicated by the identification mark.
 15. The system according to claim14, wherein the identification mark is formed by a plurality ofindicator bits, and wherein the printer includes a plurality of sensorscorresponding to the indicator bits forming the identification mark. 16.The system according to claim 12, wherein an error mark for letting thesensor detect an error is formed at every part of the sheet package orthe sheets that can be placed in the reading area of the sensor when thesheet package is set in the printer in an incorrect direction, the errormark being formed by a plurality of indicator bits indicating the sameinformation, and wherein the printer is configured to inform the user ofan error and regulate its sheet feed operation when all the sensors readthe same value.
 17. The system according to claim 11, wherein the sensoris implemented by a reflective sensor.